Commonly used thermal neutron detectors, such as gas proportional counters and scintillation counters, have the drawback of being bulky (not very portable) and are not capable of, or readily configured for, determination of the neutron flux direction (or the direction of a neutron source, which is opposite to neutron flux direction). Gas proportional counters also require high voltages, on the order of kilovolts, which can be electronically noisy and susceptible to arcing due to environmental conditions. Solid state neutron detectors based on silicon or germanium photodiodes and phototransistors exist also, but they are quite small in size, and typically require a neutron converter foil, such as gadolinium, in front of the semiconductor device.
It is thus desirable to have a thermal neutron detector that overcomes the above-described deficiencies and that is capable of readily determining the direction of neutrons arriving from any direction.